The Influence Of Dead Time Effect On Series Wind/Solar Hybrid Generation System

Compared with the traditional parallel wind/solar hybrid generation system,the series wind/solar hybrid generation system has become an important research direction because of its advantages like better output voltage,current waveform,low harmonic content and no loop current.As an important part of the series wind/solar hybrid generation system,inverter uses lots of electronic switching devices.Because of the turn-on and turn-off time of the switching devices,it is necessary to set dead time in the process of switching to avoid the upper and lower power switches opening at the same time.However,the output voltage waveform of the series wind/solar hybrid generation system will be distorted with the dead time join in.In this thesis,the effect of dead time on the output voltage of the series wind/solar hybrid generation system is analyzed,meanwhile the corresponding method of dead time compensation is studied.Firstly,the concrete structure of the series wind/solar hybrid generation system is introduced,and the characteristics of main modules like wind power generation unit,photovoltaic power generation unit and energy storage unit in the power generation system are described in detail.Secondly,the equivalent mathematical model of the dead time effect in the series wind/solar hybrid generation system is established.Based on the mathematical model,the influence of the dead time effect on the output voltage of the series wind/solar hybrid generation system that under the carrier phase shift-SPWM modulation mode is analyzed when the modulation ratio or the carrier ratio or the DC side voltage changes.The influence of the dead time effect is simulated by Simulink software.Finally,based on the analysis of dead time compensation principle in the series wind/solar hybrid generation system,a method that called carrier amplitude vary compensation method is studied for it.This method divides the output current of the series wind/solar hybrid generation system into a few region and calculates the compensation voltage required by each inverter unit in different current regions.Then,the carrier voltage of each inverter unit is adjusted to complete the dead time compensation by feedforward way.Finally,the carrier amplitude vary compensation method is verified by simulation.